<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>双向绑定</title>
</head>

<body>
    <div id="app">
        下拉框：
        <select v-model="selected">
            <option>--请选择--</option>
            <option>A</option>
            <option>B</option>
            <option>C</option>
        </select>
        <span> value:{{selected}}</span>
    </div>

    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
    <script>
        var vm = new Vue({
            el: "#app",
            data: {
                selected: ''
            }
        });
    </script>
</body>

</html>